Fluids, both liquid and gaseous, which are left untreated in pipes and containers, generally develop significant growth of bacteria, viruses and other microorganisms. Such growth occurs in both open systems and in systems which are fully enclosed and where air is excluded. Fully enclosed systems, essentially devoid of oxygen, will generally develop anaerobic growth. Open systems will develop a mixture of aerobic and anaerobic growth. The microorganisms often partition themselves into free-floating groups and may flow through the system or become attached to the walls of the container, tubing or piping. This can result in corrosion of the container, or mechanical blockage of pipes or tubes. In addition, the microbial growth or its subsequent debris can cause product contamination, product failure and disease. Therefore, it is usually desirable to destroy any microorganisms that are present in fluids, and also to prevent new microbial growth.
It is known practice to use chemical treatments to destroy microorganisms in fluids, particularly liquids. For example, chlorination or other halogenation treatments are known to be useful in purifying water. However, with chemical treatments, the amount of chemical required is highly dependent on the level of contamination in the fluid. Using too little chemical results in incomplete destruction of the microorganisms. Using too much chemical can result in contaminating the fluid with the chemical. In addition, such chemicals can be corrosive, deleteriously reactive with other chemicals in the fluid, of environmental concern, or prohibitively expensive.
Nonchemical treatments to destroy microbial growth include exposure to high intensity-ultraviolet light. The fluid generally is exposed through a transparent section of the fluid conduit by an external radiation source. Alternatively, the source can be placed inside the fluid conduit, with appropriate shielding from the fluid when necessary. Such practices can be partially effective in killing unwanted microorganisms in the fluids at the point of application to reduce the number of microorganisms and their associated debris downstream. However, such an approach does nothing to reduce the microbial population upstream from the source, and does not retard the growth of microoranisms which survive the exposure and continue downstream. Furthermore, considerable growth can occur from such microorganisms, especially if the fluid flow is interrupted for any significant amount of time.
It therefore would be desirable to have an improved process for the purification of fluids, and maintenance of high purity fluids, which does not suffer from the above-described disadvantages.